Extreme Dwarf Planet Discovered in Search for Planet X

Discovered in part with DECam at CTIO, a new dwarf planet patrols the outer Solar System on a highly elongated orbit: it travels within 65 AU of the Sun at closest approach and as far away as 1000 AU. With its distant orbit, the small planet (300 kilometers in diameter) is sensitive to the dynamics at the edge of the Solar System — and the presence of more massive outer Solar System planets, such as the hypothetical Planet X.